Circuit breaker



Patented July 11, 1950 UNITED STATES PATENT OFFICE CIRCUIT BREAKER Richard C. Ingwersen, Jackson, Mich., assigner to Mechanical Products, Inc., Jackson, Mich., a corporation of Michigan Application July 11, 1946, Serial No. 682,735 4 claims. (c1. zoo-116) The present invention relates to a resettable overload switch, especially designed for installation in home lighting and similar electrical circuits. At the present time inexpensive, nonreplaceable fusible link fuses are generally used varying from to 30 amperes in capacity at 110 volts. These devices, although inexpensive, are troublesome to detect following an overload, with most people being timid about removing the same and replacing them with new ones. More particularly, the present invention is an improvement of the construction disclosed and claimed in my co-pending application Serial No. 599,805, led June 16th, 1945, for Bimetallic Overload Circuit Breaker.

While simple, inexpensive resettable overload switches capable of being inserted into the standard household fuse sockets have heretofore been proposed, their design has not been such as to permit their approval by the re underwriters. Although overload switches of the type above described are principally designed for and used with alternating current, in order to be approved for installation they are required to function on test under extremely heavy direct current loads.

The circuit breaker according to the present invention and as described in the aforesaid application is resettable after the circuit in which it is included is opened by an overload. However, in the form of the invention disclosed in said application, the resetting provisions under certain conditions permitted an arcing at the contacts due to the relatively slow speed of resetting them. An object of the present invention is to eliminate such arcing by providing a spring member to yieldingly hold movable contacts against engaging xed contacts until a predetermined resetting force is applied. At such time the spring member releases the movable contact supporting structure suddenly, with the result that the movable contacts are moved at a high rate of speed into engagement with the xed contacts, thereby minimizing arcing. l

The foregoing objects and others residing in the arrangement and combination of parts will be more fully understood from a consideration of the following specification and annexed claims:

In the drawing.

Fig. I is a side elevational view of one form of the circuit breaker,

Fig. II is a cross-sectional view, partly broken away, taken on line II-II of Fig. I,

Fig. III is a cross-sectional view taken on line III-III of Fig. VII,

Fig. IV is a schematic layout showing the conductive parts with the switch closed,

Fig. V is a view similar to Fig. IV with the switch open,

Fig. VI is an enlarged fragmentary elevational view of a detail of construction, and

Fig. VII is an end View of Fig. I.

Referring to the drawing, in Fig. I is shown the compact form the present invention may take for screw-in installation into a standard outlet for fusible link fuses used in household lighting or other similar circuits carrying normally in the order of 15 to 20 amperes 'of alternating current.

While I do not wish to be restricted to any specific housing design other than limited by the appended claims, the illustrated form has numerous advantages. The main housing I0 cornprises two similar sections I2 and I4 of molded insulating material. The lower ends of the sections I2 and I4 have integral'threaded portions I6 to receive the internally and externally threaded metallic conductor ferrule I8. The ferrule performs three functions, namely, that of holding the sections I2 and I4 in assembly, acting as a conductor, and holding a closure plate 20 in abutment with the lower open end of the housing I0. As shown, the plate 20 is of molded insulating material with a flange 22 under which the flange 24 of the ferrule I8 engages.

Conductive inserts 26 and 28, carrying the contacts 30 are recessed in complementary channels in the sections I2 and I4. 'I'he inserts 26 and 28 serve to key the sections I2 and I4 together. Insert 28 comes to the outer surface of the section I4 where it is exposed for a solder joint with ferrule I8 at 32. This integral joint at 32 also serves to x the ferrule I8 and sections I2 and I4 in a permanently assembled state. A metallic cap 29 is disposed over the outer ends of the sections I2 and I4 to further assist in the holding of these sections together.

The cavity 38 defined by the sections I2 and I4 is enlarged at 40 to form the separable contact chamber into which the contacts 30 extend A conductor stud 42 is threaded through the plate 20 to receive a nut 44 which functions to clamp the lower end of the insert 26 and a spring clip 45 against the plate 20. Through this arrangement the insert 26 is brought into good electrical contact with the conductor stud 42 through the nut 44. As an extension of the stud 42 is a pilot portion 48 forthe spring 50.

To describe the switch parts having movement upon overload, at the time of reset, the reset button 52 projects through the opening 54 in the housing l0. An open switch indicating band 58 provides visual indication of the circuit in which the overload has occurred. As shown in Fig. II, with the switch closed, the band 5t is hidden from view.

The button 52 is enlarged at the lower end to provide a chamber 60 for receiving the upper end of the spring 50. Lateral ears 62 provide anchors for the lower ends of the springs 64.

Loosely mounted upon the shank 58 of the button 52 for both unitary and relative movement is the thermal circuit breaker unit 68. This unit comprises lateral arms 66 carrying the contacts 68 in opposed relation to the contacts 38. The

upper portions of the unit 63 embrace the shank 58 and loosely guide the unit S3 thereon. Projecting downwardly on opposite sides of the shank 58 are bimetallic supports 12 normally stressed inwardly to engage notches 14 in the shank 58. The upper ends of the springs 64 are attached to the unit 63 at 16 to stress the unit 63 downwardly with movement resisted by the engagement between the supports 12 and the notches 14.

In Figs. IV and V the relative positions of the principal parts of the switch are shown diagrammatically illustrated in open and closed position. With the switch open as shown in Fig. V, the arms 6B are supported on the shoulder 18 (shown in Fig. II) with the tension springs 64 substantially contracted, as shown in Fig. III. To close the switch, the button 52 is pushed inwardly, compressing the spring 50 and lowering the notches 14 to the position below the lower ends of the portions 12 as shown in Fig. VI. In this position the springs 64 arev under tension. At the same time the spring clip 45 will engage the abutment 15 at the bottom of the shank 58 to hold the button 52 against the action of the spring 50. Upon pulling the button 52, the compression of the spring 50 will move the shank 58 upwardly with respect to the unit 63 to seat the supports 12 in the notches 14 and then raise the unit B3 into the position shown in Fig. II, with the contacts 30 and 68 abutting under the stress of the spring 50. The function of the clip 45 is to cause the shank 58 to be suddenly released upon resetting actuation of the button 52 to close the contacts 30 and 68 with a snap action.

In the event of an overload, the excessive current ilowing through the divided path deiined by the bimetallic supports 12, will result in rapid movement of the portions 12 from the notches 14 into the position shown in Fig. III, releasing the unit B3 to move downwardly under the action of the springs 64. As a result, the contacts 30 and 68 are suddenly separated, the spacing of the contacts being determined by the location of the shoulder 18. At the same time, the spring 58 is free to move the button 52 upwardly to the position shown in Fig. III until the shoulder 80 urges the sealing washer 8| against the housing I0 as a stop. Upon observing the indicating line 56, a person is advised that the contacts 30 and 58 are open and may reset the switch by pushing and then pulling the button 52. This will bring the supports 12 into engagement with the notches 14, providing the overload has been removed. Upon releasing the button 52, the stress in the spring 5B holds the contacts 38 and 68 closed.

Structural features of the present development which contribute substantially to the ability of the unit to handle heavy direct current overloada without damage to the structure, include substantial insulation of conductors 26 and 28. maxi- :mum spacing of the contacts 30 and 58 upon overload determined by location of the shoulder 18, and division or thermally active structure between the supports 12. Also, the spring clip Q5 results in a closing of the contacts Sii and 68 with a strong snap action to minimize arcing,

The present invention primarily is an improvement over my aforesaid co-pending application, but is not intended to be limited to any particular form. Thus, not only may an equivalent be substituted for the structure of said copending application, but also the spring clip 5 may take various forms.

Having thus described my invention, what I desire to cover by Letters Patent and claim is:

1. A resettableoverload switch comprising a iixed contact, a movable contact, an actuator, a thermal latch carrying said movable contact and guided upon said actuator for axial movement relative thereto, a catch on said actuator with which said latch normally engages for unitary movement of said latch and actuator in a contact closing direction, a spring continuously biasing said actuator in a contact closing direction to hold said contacts together under spring tension, a spring stretched between said latch andv said actuator in a, contact opening direction to disengage said contacts and to impart relative axial movement to said latch and actuator upon thermal actuation of said latch out of engagement with said catch, an abutment limiting the movement of said actuator 1n a contact closing direction upon thermal disengagement of said latch and catch, an abutment with which said latch engages upon movement of said actuator in a contact opening direction to pro`v vide relative axial movement between said latch and actuator to stretch said second spring and to bring said latch and catch into re-engagement following an overload, said actuator thereu after being released to the contact engaging action oi said iirst spring, a releasable gripping means for said actuator with which said actuator engages upon movement of said actuator in a direction to re-engage said latch and catch, said means holding said actuator against movement in a contact closing direction under the biasing action of said iirst spring, said actuator being manually movable in said contact closing direction to overcome said gripping means to close said contacts with snap action.

2. A resettable overload switch as defined in claim 1 wherein said releasable gripping means is in the form of a spring clip engaging with said actuator.

3. A resettable overload switch as deiined in claim 1 wherein said actuator and said releasable gripping means are so constructed and arranged to be in operative association with one another during only partial movement of said actuator in contact closing direction.

4. A resettable overload switch comprising a iixed contact, a movable contact, an actuator, a thermal latch mechanism releasably connecting said movable contact with said actuator and normally connecting said movable contact and said actuator for unitary movement in a contact closing direction, a spring incorporated with said thermal latch mechanism and adapted to urge said movable contact to the open position upon release of the latch mechanism :from said actuator, a spring continuously acting upon said actuator for biasing said actuator in a contact closing direction, and a releasable gripping means in which said actuator engages at the end of its movement in a contact opening direction, said actuator being manually moved in a contact closing direction to overcome said grip- 5 ping means with snap action, whereby said contacts are closed with snap action by said actuator spring when the actuator is so moved and the said gripping means are overcome.

RICHARD C. INGWERSEN.

REFERENCES CITED The following references are of record in the me of this patent:

UNITED STATES PATENTS Number Name Date 1,812,842 Sachs June 30, 1931 1,886,517 Batcheller Nov. 8, 1932 2,210,261 Sachs Aug. 6, 1940 10 2,222,963 Tregoning Nov. 26, 1940 

